This invention relates to a vinylidene fluoride resin filament having high knot strength and a process for producing the same.
Vinylidene fluoride resin filaments have almost ideal characteristics as filaments for fishery uses, but their monofilaments are readily broken at knots, and therefore further improvement in knot strength has been desired. The knot strength increases with decrease in the filament diameter, but smaller diameters will result in, as a matter of course, lowering of tensile strength and knot tenacity which is defined by "(knot strength).times.(cross-section area of the filament)". Increasing of orientation up to a certain degree of orientation will also improve the knot strength, but an orientation exceeding such a degree contrariwise lowers the knot strength. Improvement of knot strength is also expected theoretically by increasing the degree of polymerization, but an increase of the degree of polymerization will bring about lowering of processability, whereby realization of high knot strength has also been limited. Thus, obtention of high knot strength without impairing other practically important physical properties and processability has been limited.